Add extern to *_main global variable declarations in header files.

- Global variables declared in header files without
  the use of the 'extern' keword will result in multiple
  instances of the variable to be created by the compiler
  -- one for each different source file in which the
  the header file is included.  This results in wasted
  memory allocated in the BSS segments as well as
  potentially introducing bugs in the application.

Change-Id: I6ef1790b60a0bd9dd3994f8510723decf258b0cc
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>

3 files changed, 4 insertions, 2 deletions

diff --git a/src/vnet/l2/l2_learn.c b/src/vnet/l2/l2_learn.c
index fddab82426c..6ece1a3c7f2 100644
--- a/src/vnet/l2/l2_learn.c
+++ b/src/vnet/l2/l2_learn.c
@@ -29,6 +29,8 @@
 #include <vppinfra/error.h>
 #include <vppinfra/hash.h>
 
+l2learn_main_t l2learn_main;
+
 /**
  * @file
  * @brief Ethernet Bridge Learning.
diff --git a/src/vnet/l2/l2_learn.h b/src/vnet/l2/l2_learn.h
index 3aaf48e2544..c1071450852 100644
--- a/src/vnet/l2/l2_learn.h
+++ b/src/vnet/l2/l2_learn.h
@@ -48,7 +48,7 @@ typedef struct
 
 #define L2LEARN_DEFAULT_LIMIT (L2FIB_NUM_BUCKETS * 64)
 
-l2learn_main_t l2learn_main;
+extern l2learn_main_t l2learn_main;
 
 extern vlib_node_registration_t l2fib_mac_age_scanner_process_node;
 
diff --git a/src/vnet/l2/l2_output.h b/src/vnet/l2/l2_output.h
index 1a73fdf9790..3b6e480d1dc 100644
--- a/src/vnet/l2/l2_output.h
+++ b/src/vnet/l2/l2_output.h
@@ -75,7 +75,7 @@ typedef struct
   vnet_main_t *vnet_main;
 } l2output_main_t;
 
-l2output_main_t l2output_main;
+extern l2output_main_t l2output_main;
 
 extern vlib_node_registration_t l2output_node;